Libraries are loaded into the process address space using the mmap system call. Conveniently, this happens to be a good time to update the process symbol table with the library's incoming symbols so we handle the table update from within the system call. This works just like an application's normal symbols. The only difference between a dynamic library and a main executable is when the symbol table update occurs. The symbol table update for an executable happens at program load time and is finished before the process ever begins executing. Since dynamic linking happens at runtime, the symbol loading happens after the library is first loaded into the process address space. The library binary is examined at this time for a symbol section and that section is parsed for symbol types with specific bindings (global, local, weak). Subsequently, these symbols are added to the table and are available for use by gem5 for things like trace generation. Checkpointing should work just as it did previously. The address space (and therefore the library) will be recorded and the symbol table will be entirely recorded. (It's not possible to do anything clever like checkpoint a program and then load the program back with different libraries with LD_LIBRARY_PATH, because the library becomes part of the address space after being loaded.)
196 lines
6 KiB
C++
196 lines
6 KiB
C++
/*
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* Copyright (c) 2013 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Anthony Gutierrez
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*/
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#include <sys/mman.h>
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#include <err.h>
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#include <unistd.h>
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#include <cassert>
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#include "base/loader/dtb_object.hh"
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#include "sim/byteswap.hh"
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#include "fdt.h"
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#include "libfdt.h"
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ObjectFile *
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DtbObject::tryFile(const std::string &fname, size_t len, uint8_t *data)
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{
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// Check if this is a FDT file by looking for magic number
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if (fdt_magic((void*)data) == FDT_MAGIC) {
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return new DtbObject(fname, len, data,
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ObjectFile::UnknownArch, ObjectFile::UnknownOpSys);
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} else {
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return NULL;
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}
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}
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DtbObject::DtbObject(const std::string &_filename, size_t _len, uint8_t *_data,
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Arch _arch, OpSys _opSys)
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: ObjectFile(_filename, _len, _data, _arch, _opSys)
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{
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text.baseAddr = 0;
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text.size = len;
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text.fileImage = fileData;
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data.baseAddr = 0;
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data.size = 0;
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data.fileImage = NULL;
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bss.baseAddr = 0;
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bss.size = 0;
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bss.fileImage = NULL;
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fileDataMmapped = true;
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}
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DtbObject::~DtbObject()
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{
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// Make sure to clean up memory properly depending
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// on how buffer was allocated.
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if (fileData && !fileDataMmapped) {
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delete [] fileData;
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fileData = NULL;
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} else if (fileData) {
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munmap(fileData, len);
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fileData = NULL;
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}
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}
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bool
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DtbObject::addBootCmdLine(const char* _args, size_t len)
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{
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const char* root_path = "/";
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const char* node_name = "chosen";
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const char* full_path_node_name = "/chosen";
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const char* property_name = "bootargs";
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// Make a new buffer that has extra space to add nodes/properties
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int newLen = 2*this->len;
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uint8_t* fdt_buf_w_space = new uint8_t[newLen];
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// Copy and unpack flattened device tree into new buffer
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int ret = fdt_open_into((void*)fileData, (void*)fdt_buf_w_space, (newLen));
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if (ret < 0) {
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warn("Error resizing buffer of flattened device tree, "
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"errno: %d\n", ret);
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delete [] fdt_buf_w_space;
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return false;
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}
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// First try finding the /chosen node in the dtb
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int offset = fdt_path_offset((void*)fdt_buf_w_space, full_path_node_name);
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if (offset < 0) {
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// try adding the node by walking dtb tree to proper insertion point
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offset = fdt_path_offset((void*)fdt_buf_w_space, root_path);
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offset = fdt_add_subnode((void*)fdt_buf_w_space, offset, node_name);
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// if we successfully add the subnode, get the offset
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if (offset >= 0)
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offset = fdt_path_offset((void*)fdt_buf_w_space, full_path_node_name);
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if (offset < 0) {
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warn("Error finding or adding \"chosen\" subnode to flattened "
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"device tree, errno: %d\n", offset);
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delete [] fdt_buf_w_space;
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return false;
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}
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}
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// Set the bootargs property in the /chosen node
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ret = fdt_setprop((void*)fdt_buf_w_space, offset, property_name,
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(const void*)_args, len+1);
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if (ret < 0) {
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warn("Error setting \"bootargs\" property to flattened device tree, "
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"errno: %d\n", ret);
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delete [] fdt_buf_w_space;
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return false;
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}
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// Repack the dtb for kernel use
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ret = fdt_pack((void*)fdt_buf_w_space);
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if (ret < 0) {
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warn("Error re-packing flattened device tree structure, "
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"errno: %d\n", ret);
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delete [] fdt_buf_w_space;
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return false;
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}
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text.size = newLen;
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text.fileImage = fdt_buf_w_space;
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// clean up old buffer and set to new fdt blob
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munmap(fileData, this->len);
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fileData = fdt_buf_w_space;
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fileDataMmapped = false;
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this->len = newLen;
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return true;
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}
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Addr
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DtbObject::findReleaseAddr()
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{
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void *fd = (void*)fileData;
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int offset = fdt_path_offset(fd, "/cpus/cpu@0");
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int len;
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const void* temp = fdt_getprop(fd, offset, "cpu-release-addr", &len);
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Addr rel_addr = 0;
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if (len > 3)
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rel_addr = betoh(*static_cast<const uint32_t*>(temp));
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if (len == 8)
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rel_addr = (rel_addr << 32) | betoh(*(static_cast<const uint32_t*>(temp)+1));
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return rel_addr;
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}
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bool
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DtbObject::loadAllSymbols(SymbolTable *symtab, Addr base, Addr offset,
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Addr addr_mask)
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{
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return false;
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}
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bool
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DtbObject::loadGlobalSymbols(SymbolTable *symtab, Addr base, Addr offset,
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Addr addr_mask)
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{
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// nothing to do here
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return false;
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}
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bool
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DtbObject::loadLocalSymbols(SymbolTable *symtab, Addr base, Addr offset,
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Addr addr_mask)
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{
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// nothing to do here
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return false;
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}
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